A light emitting diode is an inorganic semiconductor device capable of emitting light through recombination of electrons and holes and is used in various fields including displays, vehicle lamps, general lighting, and the like. A light emitting diode has various merits such as long lifespan, low power consumption and rapid response, and a light emitting device package including such a light emitting diode is expected to replace conventional light sources. Due to various merits of the light emitting diode, the light emitting device package is applied to various fields, for example, a vehicle lamp and a backlight unit.
A typical light emitting device package generally includes a substrate, a light emitting chip mounted on the substrate, an encapsulation material encapsulating the light emitting chip, a housing supporting the encapsulation material, and a lens disposed on the light emitting chip. However, the typical light emitting device package requires a separate packaging process independent of a process of manufacturing a light emitting chip, thereby causing complication of the manufacturing process while increasing manufacturing costs. Moreover, since such a light emitting device package requires a substrate for mounting the light emitting chip, there is a limit in miniaturization of the package.
In order to simplify the process of manufacturing such a light emitting device package, a wafer level process is disclosed in Korean Patent Publication No. 10-2012-0119350 A and the like. Korean Patent Publication No. 10-2012-0119350 A discloses a method of manufacturing a light emitting device module, in which a light emitting device is directly mounted on a substrate and a lens surrounding the light emitting device is directly mounted on the substrate, thereby minimizing and simplifying the manufacturing process.
However, the light emitting device module disclosed in the publication requires the substrate for forming the lens. Thus, in order to manufacture a light emitting apparatus like the light emitting device module, it is necessary to provide a packaging process for mounting the light emitting device on the substrate, and the light emitting device must include a secondary substrate in addition to a growth substrate. Such a typical light emitting apparatus cannot be regarded as a wafer level package, which does not employ other substrates except the growth substrate, and has a limit in miniaturization.
In addition, when a light emitting diode is applied to a vehicle lamp and a backlight unit, a light emitting device package including such a light emitting diode can suffer from a problem of light leakage. As used herein, light leakage means leakage of light through a side surface of the light emitting device package. That is, light leakage means that light leaks through other regions of the light emitting device package such as the side surface thereof instead of illuminating a region in front of the light emitting device package.
When light leakage occurs from the light emitting device package in the vehicle lamp, a cutoff line corresponding to a border line between a bright section and a dark section generated upon illumination of a region in front of the vehicle lamp with light emitted from the vehicle lamp becomes unclear. As a result, an undesired region is illuminated upon driving of a vehicle, causing hindrance of sight of other drivers, and the light emitting device package suffers from light loss due to light leakage through the side surface thereof.
In addition, when light leakage occurs from the light emitting device package in the backlight unit, an outer periphery of a display becomes brighter than a central region thereof or spots can be generated over the display screen. In some cases, the display can suffer from deterioration in contrast ratio and reduction of viewing angle. Moreover, the display can suffer from color deviation, thereby causing deterioration of image quality.
Korean Patent No. 10-0519592 (Registration Date: Sep. 29, 2005) discloses a light emitting diode display capable of preventing light leakage. The light emitting diode display includes a light emitting diode (LED) chip and a reflector, on which a light absorption sheet and a light absorption layer are disposed to absorb light scattered at an edge of an upper surface of the reflector. This light emitting diode display prevents light leakage by guiding light emitted from the light emitting diode chip to meet a structure for prevention of light leakage after traveling through air. Thus, this light emitting diode display has a large volume and allows a limited number of light emitting diodes (LEDs) to be mounted on a printed circuit board. Moreover, a secondary substrate must be provided together with a growth substrate to a light emitting device, thereby causing a limit in miniaturization of the light emitting device.